Metal Detector

Abstract

A metal detector in a cover of a container, including a first winding; an inner winding with a surface area that is less than that of the first winding; and an outer winding with a surface area that is greater than that of the first winding. The inner winding is connected in series with the outer winding such that a magnetic coupling between (a) the first winding and (b) the inner and outer windings connected in series is substantially zero. Shapes, locations and numbers of turns of the inner winding and the outer winding are selected such that the metal detector is less sensitive to a metal object outside the outer winding than inside the outer winding.

Dependencies are inferred from the claim text.